Abstract: We update our global evidence on the long-term realized equity risk premium, relative to both bills and bonds, in 19 different countries. Our study now runs from 1900 to the start of 2011. While there is considerable variation across countries, the realized equity risk premium was substantial everywhere. For our 19-country World index, over the entire 111 years, geometric mean real returns were an annualized 5.5%; the equity premium relative to Treasury bills was an annualized 4.5%; and the equity premium relative to long-term government bonds was an annualized 3.8%. The expected equity premium is lower, around 3% to 3½% on an annualized basis.

Diversification return is an incremental return earned by a rebalanced portfolio of assets. The diversification return of a rebalanced portfolio is often incorrectly ascribed to a reduction in variance. We argue that the underlying source of the diversification return is the rebalancing, which forces the investor to sell assets that have appreciated in relative value and buy assets that have declined in relative value, as measured by their weights in the portfolio. In contrast, the incremental return of a buy-and-hold portfolio is driven by the fact that the assets that perform the best become a greater fraction of the portfolio. We use these results to resolve two puzzles associated with the Gorton and Rouwenhorst index of commodity futures, and thereby obtain a clear understanding of the source of the return of that index. Diversification return can be a significant source of return for any rebalanced portfolio of volatile assets.

The wider theme of this conference is about what we have learned from the recent crisis. There have been many lessons. Some are not new but just a re-learning of old lore: ‘banks need to hold adequate capital’; ‘real-estate prices can fall dramatically’; ‘financial institutions need to avoid excessive risk taking’. The authorities are pursuing a long list of regulatory initiatives to address the externalities arising from risks in banks and markets, including Dodd-Frank in the US, the European Market Infrastructure Regulation (EMIR) in Europe, the Independent Commission on Banking (ICB) in the United Kingdom and the various Basel capital and liquidity rules internationally. And the Financial Stability Board has taken on a role in co-ordinating much of the other international effort. Academic research also has a large part to play in this process, in both identifying the issues and proposing or evaluating policy responses.

The downside risk of a portfolio of assets is generally substantially higher than the downside risk of its components. In times of crisis, when assets tend to have high correlation, the understanding of this difference can be crucial in managing the systemic risk of a portfolio.
In this article, Alex Langnau and Daniel Cangemi generalise Merton’s option formula in the presence of jumps to the multi-asset case. The methodology provides a new way to mark and risk-manage the systemic risk of portfolios in a systematic way.